A common type of imaging device is a pulse-echo imaging device comprising multiple transducers that transmit pulses towards a target to be imaged. The imaging device receives echoes that are reflected from the target back to the transducers. By analyzing these echoes, the imaging device creates an image of the target that reflected the pulses. An example of such a pulse-echo imaging device is an ultrasound imaging device. Beamforming is a common signal-processing technique used in ultrasound imaging devices. A beamformer generates signals to be transmitted by a transducer array and processes the echo signals received by the transducers. An image is generated from the beamformer output signal and is then displayed to the user.
Using beamforming techniques, the ultrasound imaging device can control directional and spatial aspects of the transmitted and received signals. In medical ultrasound, beamforming focuses echo signals received from reflections off different tissue structures. The receive beamformer creates a pattern of beams that are pointing in the same direction. Focusing is achieved by appropriately delaying the echo signals arriving at different transducers so that the received signals are aligned in an isophase plane.
Ultrasound machines typically comprise three distinct subsystems: a probe that includes the transducer elements, a front-end electronics section, and a back-end processor section that includes a user interface and display. It is typical for the probe to be separate from the front-end electronics section and to be coupled the front-end electronics by a cable assembly. The front-end and back-end electronics may be in a single device or in separate components. The subsystems in the ultrasound machine may be coupled using cable or wireline connections or over a wireless interface.
As ultrasound transducers increase in number and complexity, a corresponding increase is created in the amount and speed of data that must be transmitted and processed within ultrasound imaging devices. For example, ultrasound probes may employ tens of transducers for improved focusing. A typical phased-array ultrasound probe has 64-256 transducers each operating at a sampling frequency of 25-60 MHz and having a typical sampling resolution of 12 bits. As a result, the data throughput from the transducers to a receiver beamformer in a digital front end is in the order of tens of gigabits per second. This high throughput complicates the input/output interface of the digital front end of the ultrasound receiver by raising the threat of signal interference and loss along a transmission line leading from an analog front end to a digital front end in the ultrasound unit.